Oganesson << OH gah NEH sun >> is an artificially produced radioactive chemical element. It has the chemical symbol Og and anatomic number (number of protons) of 118.
In 2002, the creation of a single atom of element 118 was announced by Russian and American physicists and chemists working at the Joint Institute for Nuclear Research in Dubna (near Moscow). The group announced the creation of two more atoms of the element in 2005. In 2015, the International Union of Pure and Applied Chemistry (IUPAC) assigned credit for the discovery of the element to the Dubna team and a collaborating team at the Lawrence Livermore National Laboratory in Livermore, California. IUPAC is the recognized authority in crediting the discovery of elements and assigning names to them. Element 118 was officially named oganesson in 2016, in honor of the Russian nuclear physicist Yuri Oganessian. Oganessian leads the Flerov Laboratory of Nuclear Reactions, the division of the Joint Institute that has discovered several elements. Oganesson is the second element to be named after a living person. In 1997, element 106 was named seaborgium in honor of the American chemist Glenn T. Seaborg, who was alive at the time.
All three atoms created at Dubna were atoms of the same isotope. Isotopes are forms of an element with the same number of protons but different numbers of neutrons. Each atom of element 118 had an atomic mass number (total number of protons and neutrons) of 294. The scientists created oganesson in a device known as a particle accelerator. They bombarded the element californium, which has an atomic number of 98, with calcium, atomic number 20.
The researchers estimated that the half-life of isotope 294 is 0.89 millisecond—that is, due to radioactive decay, only half the atoms in a sample of isotope 294 would still be atoms of that isotope after less than a thousandth of a second. To determine an isotope’s half-life with much accuracy, scientists must study many atoms of the isotope. When only a few atoms have been detected—as in the case of isotope 294—they can obtain only an approximate value of the half-life.
In the periodic table of the elements, oganesson is included in Group 18 (8A) with the noble gases, a family of elements that includes neon and argon. Elements in the same family group have related properties because they have the same arrangement of electrons in their outermost or valence shell. Scientists can predict some of the properties of oganesson from its position in the periodic table. However, it is not possible to confirm some of these predictions because oganesson is so unstable and because scientists would have to obtain many more atoms of the element.
